Window regulators aren't rocket science as long as you have the tools and enough time you should be able to change them out yourself HERE is a link to some regulators for the E39 M5, there are a few great DIYs running around on youtube that could help you out.

Fluid changes are the same on an M5 as any other vehicle, just make sure you get the correct fluids; BMW Antifreeze/Coolant LINK, Castrol 10w/60 Synthetic Engine Oil LINK, etc